[DIY Template] Size of the page and page's positioning Options

[adamchen]

Hello, dear admin:

I DIYed a template and it seems has a FIXED width that makes my customized header looks very strange once the screen size of the viewer changes.
For example, I made a header size 780*150, once my screen is 1440*900, the header will not stretch by itself. On the other hand, once I made it a header size 1440*150, It becomes too big for a screen of 1024*768. The ultimate result is that the content space below the header become way too strechy for the viewer and they have to move the page around.

Is there a way to let my page fix viewer's screen or let the page automatically center the header, footer, and content, anyway the whole page...Would you like to help me out? I am frustrated ioi

Thank you